The present invention relates to an opening shield plate used as an opening shield lid of an electrolyte capacitor.
A opening shield plate 51 shown in FIG. 6 is conventionally known and structured as follows.
Namely, first of all, a resin made opening shield member 53 in the form of a plate to be pressed to fix to a circumferential edge portion of an upper opening portion of a capacitor case 52 is provided. Aluminum terminals 54 are bonded to the resin made opening shield member 53 by an insert molding. As known well, in the insert molding, the aluminum terminals 54 are inserted into a cavity of molds for molding the resin made opening shield member 53 for molding, and the two components 53 and 54 are bonded to each other simultaneously with the completion of the molding.
A packing 55 made of rubber elastic material is interposed between the capacitor case 52 and the resin made shield member 53 in order to prevent the electrolyte contained in the case 52 from leaking to the outside from the press-fit portion between the resin made opening shield member 53 and the capacitor case 52. Reference numeral 56 denotes a capacitor element received in the interior of the capacitor case 52, reference numeral 57 denotes lead lines for connecting the capacitor element 56 and aluminum terminals 54, and reference numeral 58 denotes an explosion preventing valve for releasing an excessive pressure.
However, the above-described conventional opening shield plate 51 has the following disadvantages. Namely, in the case where an electrolyte liquid is type of a high permeation, if this electrolyte permeates into the press-fit portion to be brought into contact with the packing 55, there is a fear that the packing 55 would be deteriorated relatively earlier by the chemical reaction. Accordingly, since it is impossible to sufficiently seal the electrolyte liquid only with the deteriorated packing 55, there is a fear that the electrolyte liquid would out leak from the interface between the resin made opening shield member 53 and the capacitor case 52, i.e., the interface between the opening shield plate 51 and the capacitor case 52.
Also, with respect to the interface between the resin made opening shield member 53 and the aluminum terminals 54, there is a fear that a gap would be formed gradually due to the fact that there is a difference in thermal expansion rate or thermal transfer rate between the two components 53 and 54 and the electrolyte liquid would leak out through the gap. In this connection, the present applicant has proposed the approach that a flanged portion 54a is integrally formed with an outer circumference of each aluminum terminal 54 as shown in the drawing and the flanged portion 54a is embedded within the thickness of the resin made opening shield member 53 to enhance the bondability between the two components 53 and 54 (see Utility Model Publication No. 21222/1994). However, if the bondability between the two components 53 and 54 or the sealability there between is further enhanced, this would be by far better.